Apama Documentation : Developing Apama Applications : EPL Streams: A Quick Tour : Common stream query patterns : Throttling in stream queries
Throttling in stream queries
Sometimes it is the case that results are only required at a given rate. We can extend the example in Aggregation in stream queries by adding an every clause, so that the query generates values only every 10 seconds.
01. using com.apama.aggregates.wavg;
02. event Tick { string symbol; float price; float volume; }
03. monitor CalculateVwap {
04. action onload() {
05. float vwap;
06. from t in all Tick(symbol="SOW") within 300.0 every 10.0
07. select wavg(t.price,t.volume): vwap {
08. print vwap.toString();
09. }
10. }
11. }
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